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s390: add 'install' target to 'make help'
[linux/fpc-iii.git] / net / netfilter / xt_socket.c
blob2ec08f04b816bc863e582fed000a2143d0b688a5
1 /*
2 * Transparent proxy support for Linux/iptables
3 *
4 * Copyright (C) 2007-2008 BalaBit IT Ltd.
5 * Author: Krisztian Kovacs
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/netfilter/x_tables.h>
16 #include <linux/netfilter_ipv4/ip_tables.h>
17 #include <net/tcp.h>
18 #include <net/udp.h>
19 #include <net/icmp.h>
20 #include <net/sock.h>
21 #include <net/inet_sock.h>
22 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
23
24 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
25 #define XT_SOCKET_HAVE_IPV6 1
26 #include <linux/netfilter_ipv6/ip6_tables.h>
27 #include <net/inet6_hashtables.h>
28 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
29 #endif
30
31 #include <linux/netfilter/xt_socket.h>
32
33 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
34 #define XT_SOCKET_HAVE_CONNTRACK 1
35 #include <net/netfilter/nf_conntrack.h>
36 #endif
37
38 static int
39 extract_icmp4_fields(const struct sk_buff *skb,
40 u8 *protocol,
41 __be32 *raddr,
42 __be32 *laddr,
43 __be16 *rport,
44 __be16 *lport)
45 {
46 unsigned int outside_hdrlen = ip_hdrlen(skb);
47 struct iphdr *inside_iph, _inside_iph;
48 struct icmphdr *icmph, _icmph;
49 __be16 *ports, _ports[2];
50
51 icmph = skb_header_pointer(skb, outside_hdrlen,
52 sizeof(_icmph), &_icmph);
53 if (icmph == NULL)
54 return 1;
55
56 switch (icmph->type) {
57 case ICMP_DEST_UNREACH:
58 case ICMP_SOURCE_QUENCH:
59 case ICMP_REDIRECT:
60 case ICMP_TIME_EXCEEDED:
61 case ICMP_PARAMETERPROB:
62 break;
63 default:
64 return 1;
65 }
66
67 inside_iph = skb_header_pointer(skb, outside_hdrlen +
68 sizeof(struct icmphdr),
69 sizeof(_inside_iph), &_inside_iph);
70 if (inside_iph == NULL)
71 return 1;
72
73 if (inside_iph->protocol != IPPROTO_TCP &&
74 inside_iph->protocol != IPPROTO_UDP)
75 return 1;
76
77 ports = skb_header_pointer(skb, outside_hdrlen +
78 sizeof(struct icmphdr) +
79 (inside_iph->ihl << 2),
80 sizeof(_ports), &_ports);
81 if (ports == NULL)
82 return 1;
83
84 /* the inside IP packet is the one quoted from our side, thus
85 * its saddr is the local address */
86 *protocol = inside_iph->protocol;
87 *laddr = inside_iph->saddr;
88 *lport = ports[0];
89 *raddr = inside_iph->daddr;
90 *rport = ports[1];
91
92 return 0;
93 }
94
95 /* "socket" match based redirection (no specific rule)
96 * ===================================================
97 *
98 * There are connections with dynamic endpoints (e.g. FTP data
99 * connection) that the user is unable to add explicit rules
100 * for. These are taken care of by a generic "socket" rule. It is
101 * assumed that the proxy application is trusted to open such
102 * connections without explicit iptables rule (except of course the
103 * generic 'socket' rule). In this case the following sockets are
104 * matched in preference order:
105 *
106 * - match: if there's a fully established connection matching the
107 * _packet_ tuple
108 *
109 * - match: if there's a non-zero bound listener (possibly with a
110 * non-local address) We don't accept zero-bound listeners, since
111 * then local services could intercept traffic going through the
112 * box.
113 */
114 static struct sock *
115 xt_socket_get_sock_v4(struct net *net, const u8 protocol,
116 const __be32 saddr, const __be32 daddr,
117 const __be16 sport, const __be16 dport,
118 const struct net_device *in)
119 {
120 switch (protocol) {
121 case IPPROTO_TCP:
122 return __inet_lookup(net, &tcp_hashinfo,
123 saddr, sport, daddr, dport,
124 in->ifindex);
125 case IPPROTO_UDP:
126 return udp4_lib_lookup(net, saddr, sport, daddr, dport,
127 in->ifindex);
128 }
129 return NULL;
130 }
131
132 static bool xt_socket_sk_is_transparent(struct sock *sk)
133 {
134 switch (sk->sk_state) {
135 case TCP_TIME_WAIT:
136 return inet_twsk(sk)->tw_transparent;
137
138 case TCP_NEW_SYN_RECV:
139 return inet_rsk(inet_reqsk(sk))->no_srccheck;
140
141 default:
142 return inet_sk(sk)->transparent;
143 }
144 }
145
146 static struct sock *xt_socket_lookup_slow_v4(struct net *net,
147 const struct sk_buff *skb,
148 const struct net_device *indev)
149 {
150 const struct iphdr *iph = ip_hdr(skb);
151 __be32 uninitialized_var(daddr), uninitialized_var(saddr);
152 __be16 uninitialized_var(dport), uninitialized_var(sport);
153 u8 uninitialized_var(protocol);
154 #ifdef XT_SOCKET_HAVE_CONNTRACK
155 struct nf_conn const *ct;
156 enum ip_conntrack_info ctinfo;
157 #endif
158
159 if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
160 struct udphdr _hdr, *hp;
161
162 hp = skb_header_pointer(skb, ip_hdrlen(skb),
163 sizeof(_hdr), &_hdr);
164 if (hp == NULL)
165 return NULL;
166
167 protocol = iph->protocol;
168 saddr = iph->saddr;
169 sport = hp->source;
170 daddr = iph->daddr;
171 dport = hp->dest;
172
173 } else if (iph->protocol == IPPROTO_ICMP) {
174 if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
175 &sport, &dport))
176 return NULL;
177 } else {
178 return NULL;
179 }
180
181 #ifdef XT_SOCKET_HAVE_CONNTRACK
182 /* Do the lookup with the original socket address in
183 * case this is a reply packet of an established
184 * SNAT-ted connection.
185 */
186 ct = nf_ct_get(skb, &ctinfo);
187 if (ct && !nf_ct_is_untracked(ct) &&
188 ((iph->protocol != IPPROTO_ICMP &&
189 ctinfo == IP_CT_ESTABLISHED_REPLY) ||
190 (iph->protocol == IPPROTO_ICMP &&
191 ctinfo == IP_CT_RELATED_REPLY)) &&
192 (ct->status & IPS_SRC_NAT_DONE)) {
193
194 daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
195 dport = (iph->protocol == IPPROTO_TCP) ?
196 ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
197 ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
198 }
199 #endif
200
201 return xt_socket_get_sock_v4(net, protocol, saddr, daddr,
202 sport, dport, indev);
203 }
204
205 static bool
206 socket_match(const struct sk_buff *skb, struct xt_action_param *par,
207 const struct xt_socket_mtinfo1 *info)
208 {
209 struct sk_buff *pskb = (struct sk_buff *)skb;
210 struct sock *sk = skb->sk;
211
212 if (!sk)
213 sk = xt_socket_lookup_slow_v4(par->net, skb, par->in);
214 if (sk) {
215 bool wildcard;
216 bool transparent = true;
217
218 /* Ignore sockets listening on INADDR_ANY,
219 * unless XT_SOCKET_NOWILDCARD is set
220 */
221 wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
222 sk_fullsock(sk) &&
223 inet_sk(sk)->inet_rcv_saddr == 0);
224
225 /* Ignore non-transparent sockets,
226 * if XT_SOCKET_TRANSPARENT is used
227 */
228 if (info->flags & XT_SOCKET_TRANSPARENT)
229 transparent = xt_socket_sk_is_transparent(sk);
230
231 if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
232 transparent)
233 pskb->mark = sk->sk_mark;
234
235 if (sk != skb->sk)
236 sock_gen_put(sk);
237
238 if (wildcard || !transparent)
239 sk = NULL;
240 }
241
242 return sk != NULL;
243 }
244
245 static bool
246 socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
247 {
248 static struct xt_socket_mtinfo1 xt_info_v0 = {
249 .flags = 0,
250 };
251
252 return socket_match(skb, par, &xt_info_v0);
253 }
254
255 static bool
256 socket_mt4_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
257 {
258 return socket_match(skb, par, par->matchinfo);
259 }
260
261 #ifdef XT_SOCKET_HAVE_IPV6
262
263 static int
264 extract_icmp6_fields(const struct sk_buff *skb,
265 unsigned int outside_hdrlen,
266 int *protocol,
267 const struct in6_addr **raddr,
268 const struct in6_addr **laddr,
269 __be16 *rport,
270 __be16 *lport,
271 struct ipv6hdr *ipv6_var)
272 {
273 const struct ipv6hdr *inside_iph;
274 struct icmp6hdr *icmph, _icmph;
275 __be16 *ports, _ports[2];
276 u8 inside_nexthdr;
277 __be16 inside_fragoff;
278 int inside_hdrlen;
279
280 icmph = skb_header_pointer(skb, outside_hdrlen,
281 sizeof(_icmph), &_icmph);
282 if (icmph == NULL)
283 return 1;
284
285 if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
286 return 1;
287
288 inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph),
289 sizeof(*ipv6_var), ipv6_var);
290 if (inside_iph == NULL)
291 return 1;
292 inside_nexthdr = inside_iph->nexthdr;
293
294 inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) +
295 sizeof(*ipv6_var),
296 &inside_nexthdr, &inside_fragoff);
297 if (inside_hdrlen < 0)
298 return 1; /* hjm: Packet has no/incomplete transport layer headers. */
299
300 if (inside_nexthdr != IPPROTO_TCP &&
301 inside_nexthdr != IPPROTO_UDP)
302 return 1;
303
304 ports = skb_header_pointer(skb, inside_hdrlen,
305 sizeof(_ports), &_ports);
306 if (ports == NULL)
307 return 1;
308
309 /* the inside IP packet is the one quoted from our side, thus
310 * its saddr is the local address */
311 *protocol = inside_nexthdr;
312 *laddr = &inside_iph->saddr;
313 *lport = ports[0];
314 *raddr = &inside_iph->daddr;
315 *rport = ports[1];
316
317 return 0;
318 }
319
320 static struct sock *
321 xt_socket_get_sock_v6(struct net *net, const u8 protocol,
322 const struct in6_addr *saddr, const struct in6_addr *daddr,
323 const __be16 sport, const __be16 dport,
324 const struct net_device *in)
325 {
326 switch (protocol) {
327 case IPPROTO_TCP:
328 return inet6_lookup(net, &tcp_hashinfo,
329 saddr, sport, daddr, dport,
330 in->ifindex);
331 case IPPROTO_UDP:
332 return udp6_lib_lookup(net, saddr, sport, daddr, dport,
333 in->ifindex);
334 }
335
336 return NULL;
337 }
338
339 static struct sock *xt_socket_lookup_slow_v6(struct net *net,
340 const struct sk_buff *skb,
341 const struct net_device *indev)
342 {
343 __be16 uninitialized_var(dport), uninitialized_var(sport);
344 const struct in6_addr *daddr = NULL, *saddr = NULL;
345 struct ipv6hdr *iph = ipv6_hdr(skb);
346 int thoff = 0, tproto;
347
348 tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
349 if (tproto < 0) {
350 pr_debug("unable to find transport header in IPv6 packet, dropping\n");
351 return NULL;
352 }
353
354 if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
355 struct udphdr _hdr, *hp;
356
357 hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
358 if (hp == NULL)
359 return NULL;
360
361 saddr = &iph->saddr;
362 sport = hp->source;
363 daddr = &iph->daddr;
364 dport = hp->dest;
365
366 } else if (tproto == IPPROTO_ICMPV6) {
367 struct ipv6hdr ipv6_var;
368
369 if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
370 &sport, &dport, &ipv6_var))
371 return NULL;
372 } else {
373 return NULL;
374 }
375
376 return xt_socket_get_sock_v6(net, tproto, saddr, daddr,
377 sport, dport, indev);
378 }
379
380 static bool
381 socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
382 {
383 const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
384 struct sk_buff *pskb = (struct sk_buff *)skb;
385 struct sock *sk = skb->sk;
386
387 if (!sk)
388 sk = xt_socket_lookup_slow_v6(par->net, skb, par->in);
389 if (sk) {
390 bool wildcard;
391 bool transparent = true;
392
393 /* Ignore sockets listening on INADDR_ANY
394 * unless XT_SOCKET_NOWILDCARD is set
395 */
396 wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
397 sk_fullsock(sk) &&
398 ipv6_addr_any(&sk->sk_v6_rcv_saddr));
399
400 /* Ignore non-transparent sockets,
401 * if XT_SOCKET_TRANSPARENT is used
402 */
403 if (info->flags & XT_SOCKET_TRANSPARENT)
404 transparent = xt_socket_sk_is_transparent(sk);
405
406 if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
407 transparent)
408 pskb->mark = sk->sk_mark;
409
410 if (sk != skb->sk)
411 sock_gen_put(sk);
412
413 if (wildcard || !transparent)
414 sk = NULL;
415 }
416
417 return sk != NULL;
418 }
419 #endif
420
421 static int socket_mt_v1_check(const struct xt_mtchk_param *par)
422 {
423 const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
424
425 if (info->flags & ~XT_SOCKET_FLAGS_V1) {
426 pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1);
427 return -EINVAL;
428 }
429 return 0;
430 }
431
432 static int socket_mt_v2_check(const struct xt_mtchk_param *par)
433 {
434 const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;
435
436 if (info->flags & ~XT_SOCKET_FLAGS_V2) {
437 pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2);
438 return -EINVAL;
439 }
440 return 0;
441 }
442
443 static int socket_mt_v3_check(const struct xt_mtchk_param *par)
444 {
445 const struct xt_socket_mtinfo3 *info =
446 (struct xt_socket_mtinfo3 *)par->matchinfo;
447
448 if (info->flags & ~XT_SOCKET_FLAGS_V3) {
449 pr_info("unknown flags 0x%x\n",
450 info->flags & ~XT_SOCKET_FLAGS_V3);
451 return -EINVAL;
452 }
453 return 0;
454 }
455
456 static struct xt_match socket_mt_reg[] __read_mostly = {
457 {
458 .name = "socket",
459 .revision = 0,
460 .family = NFPROTO_IPV4,
461 .match = socket_mt4_v0,
462 .hooks = (1 << NF_INET_PRE_ROUTING) |
463 (1 << NF_INET_LOCAL_IN),
464 .me = THIS_MODULE,
465 },
466 {
467 .name = "socket",
468 .revision = 1,
469 .family = NFPROTO_IPV4,
470 .match = socket_mt4_v1_v2_v3,
471 .checkentry = socket_mt_v1_check,
472 .matchsize = sizeof(struct xt_socket_mtinfo1),
473 .hooks = (1 << NF_INET_PRE_ROUTING) |
474 (1 << NF_INET_LOCAL_IN),
475 .me = THIS_MODULE,
476 },
477 #ifdef XT_SOCKET_HAVE_IPV6
478 {
479 .name = "socket",
480 .revision = 1,
481 .family = NFPROTO_IPV6,
482 .match = socket_mt6_v1_v2_v3,
483 .checkentry = socket_mt_v1_check,
484 .matchsize = sizeof(struct xt_socket_mtinfo1),
485 .hooks = (1 << NF_INET_PRE_ROUTING) |
486 (1 << NF_INET_LOCAL_IN),
487 .me = THIS_MODULE,
488 },
489 #endif
490 {
491 .name = "socket",
492 .revision = 2,
493 .family = NFPROTO_IPV4,
494 .match = socket_mt4_v1_v2_v3,
495 .checkentry = socket_mt_v2_check,
496 .matchsize = sizeof(struct xt_socket_mtinfo1),
497 .hooks = (1 << NF_INET_PRE_ROUTING) |
498 (1 << NF_INET_LOCAL_IN),
499 .me = THIS_MODULE,
500 },
501 #ifdef XT_SOCKET_HAVE_IPV6
502 {
503 .name = "socket",
504 .revision = 2,
505 .family = NFPROTO_IPV6,
506 .match = socket_mt6_v1_v2_v3,
507 .checkentry = socket_mt_v2_check,
508 .matchsize = sizeof(struct xt_socket_mtinfo1),
509 .hooks = (1 << NF_INET_PRE_ROUTING) |
510 (1 << NF_INET_LOCAL_IN),
511 .me = THIS_MODULE,
512 },
513 #endif
514 {
515 .name = "socket",
516 .revision = 3,
517 .family = NFPROTO_IPV4,
518 .match = socket_mt4_v1_v2_v3,
519 .checkentry = socket_mt_v3_check,
520 .matchsize = sizeof(struct xt_socket_mtinfo1),
521 .hooks = (1 << NF_INET_PRE_ROUTING) |
522 (1 << NF_INET_LOCAL_IN),
523 .me = THIS_MODULE,
524 },
525 #ifdef XT_SOCKET_HAVE_IPV6
526 {
527 .name = "socket",
528 .revision = 3,
529 .family = NFPROTO_IPV6,
530 .match = socket_mt6_v1_v2_v3,
531 .checkentry = socket_mt_v3_check,
532 .matchsize = sizeof(struct xt_socket_mtinfo1),
533 .hooks = (1 << NF_INET_PRE_ROUTING) |
534 (1 << NF_INET_LOCAL_IN),
535 .me = THIS_MODULE,
536 },
537 #endif
538 };
539
540 static int __init socket_mt_init(void)
541 {
542 nf_defrag_ipv4_enable();
543 #ifdef XT_SOCKET_HAVE_IPV6
544 nf_defrag_ipv6_enable();
545 #endif
546
547 return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
548 }
549
550 static void __exit socket_mt_exit(void)
551 {
552 xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
553 }
554
555 module_init(socket_mt_init);
556 module_exit(socket_mt_exit);
557
558 MODULE_LICENSE("GPL");
559 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
560 MODULE_DESCRIPTION("x_tables socket match module");
561 MODULE_ALIAS("ipt_socket");
562 MODULE_ALIAS("ip6t_socket");
Linux with added FPC-III support